import java.util.ArrayList;
import java.util.HashMap;

public class Test {
    public static void main(String[] args) {
        HashMap<Integer,Integer> hs = new HashMap<>();
        hs.put(1,3);
        hs.put(2,3);
        hs.put(3,3);
        hs.put(4,3);
        hs.put(5,3);
        hs.put(6,3);
        hs.remove(1);
        hs.remove(2);
        hs.put(12,12);
        System.out.println(hs.keySet().contains(12));
    }
}